Many semiconductor processing tools use an end-point determination (EPD) system to call active end-point on a process chamber. Major semiconductor processing tool vendors such as Applied Materials, Lam Research, and Tokyo Electron supply processing tools equipped with optical emission spectroscopy (OES)-based EPD systems already integrated with the chambers. Using these legacy EPD systems, a process engineer can configure the EPD systems to cause a recipe step to end when specific end-point criteria are met. One example of such specific criteria is when the intensity at wavelength 780 nm falls by 20% in a 5-second window. Such criteria are defined to capture signal features that represent the end-point of that particular processing step. Actively calling end-point is beneficial because it allows control of the processing time which can counteract variations in wafer processing. By contrast, without an EPD system the processing time is fixed, regardless of variations in the wafer processing.
Although many semiconductor processing chambers come equipped with OES EPD systems as legacy components, these may not be used because their accuracy may be insufficient for production-level deployment. In recent years, third parties have offered EPD products exhibiting greater accuracy and dependability than the legacy OES EPD systems offered by major tool manufacturers. However, effective integration of such new EPD systems into the semiconductor tool can be difficult.
A variety of strategies can be attempted for integrating a new EPD system with a tool. However, these conventional approaches may offer certain limitations. For example, semiconductor tools are usually equipped with physical ports by which a legacy OES EPD system is configured to communicate with the tool. The communication protocol on these ports is usually proprietary, creating a barrier for integration of the new EPD system. Although an attempt can be made to reverse-engineer the end-point protocol, proprietary binary protocols are extremely difficult to interpret without the protocol specifications. Moreover, the procedures for proper handling of the exception cases necessary for production-level systems would not be known.
It is also possible to request the protocol specification from the original equipment manufacturer (the “OEM”). However, obtaining the cooperation of a large OEM may often be difficult.
A third conventional approach is to attempt to adopt other communications ports on the tool to interact with the new EPD system. Examples of such communications ports include the SEMI Equipment Communications Standard/High-Speed SECS Message Services (SECS/HSMS) ports commonly found on semiconductor tools. However, this approach may also not yield the desired result, as these other communications ports do not have commands tailored to end-pointing a recipe step. For example, while it may be possible to stop the step via a SECS command, processing of the wafer would stop entirely, requiring manual intervention to restore tool operation.
In view of the above, there is a need in the art for methods and apparatuses for the integration of external EPD systems into manufacturing tools.